Referring to FIGS. 1 and 2, a beverage container 100 often includes a body 102, a neck 104 and an internal volume 106. The internal volume 106 of the container 100 is often sealed by a crown 108 that is connected to a top portion 110 of the neck 104 to close off the internal volume 106 of the container 100 until a liquid 112, for example, water, beer, soda, or some other fluid, in the container is to be consumed. The container 100 and crown 108 may be made of many types of materials. In the case of a typical container 100 for beer, for example, a glass container 100 is sealed by fastening a metal crown 108 to the top portion 110 of the neck 104.
The internal volume 106 is often only partially filled with the liquid 112 so that a portion of the internal volume 106 does not include the liquid 112. The portion of the internal volume 106 that is not filled with the liquid 112 is often called the headspace 114. The headspace 114 is located near the crown 108 when the container 100 is in an upright position, as shown in FIG. 1, and may contain oxygen 116, nitrogen, another gas or a mixture of gases, depending on the technique used to fill and seal the container 100. For some liquids 112, the shelf if of the liquid 112 is influenced by the gases contained the headspace 114. For example, the shelf life of beer is negatively affected by oxygen 116 in the headspace 114.
Modern container filling techniques insert a predetermined amount of liquid 112 into the internal volume 106 while limiting the amount of oxygen 116 in the headspace 114 when the container 100 is sealed. For example, in some techniques oxygen 116 is removed from the headspace 114 by a vacuum just prior to sealing the crown 108 to the container 100. Other techniques include removing the oxygen 116 by inert gas sparging or a combination of a vacuum and inert gas sparging. However, these filling techniques have not been able to completely eliminate all oxygen 116 from the headspace 114 and total package oxygen ranging from about 30 ppb to about 1000 ppb often remain in the container 100.
In addition, oxygen 116 from the atmosphere surrounding the container 100 may enter the headspace 114 by passing between the crown 108 and the container 100. To reduce and/or prevent oxygen 116 from entering the headspace 114 in this manner and to further seal the liquid 112 in the container 100, one or more liners 118 are often attached to a bottom surface 120 of the crown 108 so as to be located between the crown 108 and the container opening 122 when the crown 108 is sealed to the container 100. Liners 118 are often made of a resilient, deformable material that allows the liner 118 to be compressed between the crown 108 and the container opening 122 when the crown 108 and liner 118 are secured to the container 100.
The liner 118 may include an oxygen scavenger that absorbs oxygen 116 that penetrates the liner 118. For example, U.S. Pat. No. 5,663,223 (“'723 patent”) describes the deleterious effects of oxygen 116 on flavor and shelf life for certain liquids 112 and identifies a liner 118 containing an oxygen scavenger as an approach to ameliorate the problem. The '223 patent discloses a liner composition designed to protect beer or other flavor sensitive liquids 112 from oxygen 116 which permeates into the container 100 through the liner 118. The '223 patent proposes a liner 118 composition comprising oxygen scavengers wherein at least two oxygen scavengers are used. Sodium sulfite is disclosed in the '223 patent as a known oxygen scavenger and the '223 patent discloses compositions containing not more than 5% by weight sodium sulfite with at least one additional oxygen scavenging compound. According to the '223 patent, the compositions disclosed therein provide a flavor that is protected up to 16 days.
The '223 patent discloses the results of the recommended compounds with an initial total package oxygen between 200 and 400 ppb and notes that it would be desirable to achieve an initial total package oxygen below 50 ppb. With modern filling techniques, initial total package oxygen of less than 50 ppb is achievable without use of an oxygen scavenger. It would be expected that as initial total package oxygen decreases, the amount of oxygen scavenger necessary to provide the same shelf life extension would be lower. Unexpectedly, it has been found that this is not the case.
In addition, many beverages and beverage containers 100 are pasteurized to reduce the amount of unwanted biological contaminants. The '223 patent does not discuss removing oxygen 116 from the headspace 114 during pasteurization or the effect of doing so. It has been found that the amount of oxygen 116 removed from the headspace 114 during pasteurization can have a significant impact on the shelf life of the liquid 112. In sum, it has been discovered that, while the compounds of the '223 patent are beneficial, they are not adequate in situations where protection much longer than 16 days is desired.
Referring now to FIG. 2, beverage manufacturers often desire to place printed material 124, for example, advertisements and/or promotions, on a bottom surface 120 of the crown 108. The advertisements are visible to the user when the crown 108 is removed from the container 100. These advertisements and promotions are often printed directly on a metal crown 108, on a varnish on the metal crown 108 or between layers of a multi-layer liner 118. It has been discovered, however, that advertisements and other printed material placed under a liner that contains an oxygen scavenger are often difficult read and become obscured as the liner absorbs oxygen 116. Thus, a newprinting method is required for liners containing oxygen scavengers.